Carbon-14

Physical Characteristics:

• Half-life: 5,730 years
• Emissions: Beta particles with a maximum energy of 156 keV and an average energy of 49 keV.
• Maximum Range in Air: 22 cm in air; 0.027 cm in tissue.
• Fraction transmitted through the dead layer of the skin: 0.11

Dose:

• Dose rate to the skin at 10 cm: 600 mrad/hour/mCi
  (for an unshielded point source)
• Dose rate to epidermal basal cells from skin contamination of 1 mCi/cm2: 1400 mrad/hour

Shielding:

• None needed, when used in millicuries quantities under normal laboratory conditions.

Annual Intake Limits (ALI)

• Ingestion: 2×103 µCi
  Note: 1.0ALI = 5,000 mrem CEDE

Detection:

• Liquid scintillation counter is the preferred method for detecting C-14. Most G-M detectors are not likely to detect the presence of C-14 in amounts less than about 0.05 µCi (100,000 dpm).
• Whole Body dosimeter: Not required
• Finger dosimeter: Not required

Precautions:
Low-level C-14 contamination cannot be easily detected with a G-M meter, and special precautions are needed to keep the work environment clean. The regular use of wipe testing, using a liquid scintillation counter, is the only way to insure that your work space does not contain low-level removable contamination.

Waste Disposal: Call r